A High Court judge has ruled that a 13-year-old girl is capable of making her own decisions about whether or not to terminate a pregnancy.

Health authority bosses had asked Mr Justice Mostyn to decide whether the teenager had the mental capacity to understand options open to her.

The judge concluded that she did - after hearing evidence from a psychiatrist who had interviewed her.

He said it was for the girl to "decide what she wishes to do".

Detail of the case emerged today in a written ruling by the judge following a hearing in the Family Division of the High Court in London.

The judge said the girl's grandmother had noticed a "bump" a few weeks ago. Tests had shown that the girl was probably more than 20 weeks pregnant.

He said health authority bosses with responsibility for the youngster's care had sought a court ruling because they wanted to be sure that the teenager had the "appropriate capacity" to make decisions about the pregnancy.

The judge did not identify anyone involved but said the girl lived in the north of England with her parents.

The ruling did not give detail of any views held by the girl's parents.

Mr Justice Mostyn said the girl would need family support.

"If she decides to continue with the pregnancy, then I am expecting that her family and, indeed, Social Services will need to give her considerable support and assistance," he added.

"It also goes without saying that should she go through with a termination her family will need to be at her side and to assist her and support her after what is inevitably going to be an unpleasant and traumatic experience."